[Table of Contents]

  1. Facts about influenza
  • Learn about influenza
  • Learn about the symptoms of influenza
  • Learn about influenza treatment
  1. Going to the hospital for influenza
  2. What to do to prevent infection

1.Facts about influenza                                                        

Let’s learn about influenza by looking at the “Influenza Countermeasures” seen on the Ministry of Health, Labor and Welfare website. (Some contents have been edited.)

<Learn about influenza>

(Question 1) What are the different types of influenza viruses?


Influenza viruses that cause influenza are classified into types A, B, and C. Of these, types A and B are the causes of major epidemics. The viruses spread all over the world every year, and the types causing the epidemics varies by country, region, and year.

(Question 2) When will influenza be prevalent?


Seasonal influenza is epidemic. Once it begins, it spreads to many people in a short period of time. In Japan, the main season is usually from December to April. 

<Learn about the symptoms of influenza>

(Question 1) What are the symptoms of influenza infection?


After a 1 to 3 days incubation period, symptoms such as fever above 38℃ (100℉), headache, joint pain, muscle pain, and fatigue would appear relatively rapidly. Just like a regular cold, symptoms such as sore throat, runny nose, and cough can be seen as well.

(Question 2) What kind of person is likely to have severe symptoms due to influenza?


More caution is required for: “elderly people,” “children,” “pregnant women,” and “people with chronic diseases (such as asthma and diabetes).”

<Learn about influenza treatment>

(Question 1) What kind of treatments are there?


Anti-influenza virus drugs are prescribed for influenza. The effect depends on the time and symptoms after the appearance of the flu symptoms. Therefore, it is up to a doctor to decide whether or not a patient has the need to use the drug.

When you start taking the anti-influenza virus drugs at the right time (within 48 hours of onset), fever period will usually be reduced by 1 to 2 days. Viral shedding from the nose and throat is also reduced. On the other hand, if you start taking the drug 48 hours after the onset, you may not expect a sufficient effect.

For effective use, it is important to stick to the directions, dosage and duration (days of taking drugs).

(Question 2) Abnormal behavior has been reported when someone gets the flu. Should I be worried?


Whether a patient was taking anti-influenza virus drugs or not, abnormal behaviors such as sudden running and wandering have been reported regardless of the type of Influenza.

Family members or housemates should be constantly keeping an eye on the patient, regardless of whether or not the person is taking anti-influenza virus drugs or its type. The care givers should pay close attention to them for at least two days after the fever.

(Question 3) How long should I stay home if I get the flu?


Typically, the virus is shed from the nose and throat from the day before the onset of influenza to 3 to 7 days after the onset. Therefore, you should refrain from going out during that period.

Although the virus decreases as fever lowers, it is said that the virus is shed even after the fever is gone. If you continue to have symptoms such as coughing or sneezing, wear a mask, and be careful not to pass it on to others.

2.Going to the hospital for influenza                                          

Please go see a doctor when you have a sudden fever of 38℃ (100℉) or higher, cough and sore throat, and fatigue. If you have any of these symptoms, seek medical care soon.

If you are an elderly person, a child, a pregnant woman, have a particular medical condition, or have any of the following symptoms, go see a doctor immediately.

Severe Signs
Convulsion, no responseDifficulty breathing or shortness of breath
Fast breathing, looking painfulPersistent pain in the chest
Pale skin colorPersistent vomiting and diarrhea
Persistent vomiting and diarrheaProlonged and worsened symptoms
Prolonged and worsened symptoms

“Source: Ministry of Health, Labor and Welfare website”

Medical Institutions for Treatment

Go to a nearby internal medicine or pediatrics.

Wear a mask when you visit the hospital and be careful not to infect others. 

If there is a family doctor (a doctor in a clinic/hospital near your home), you can rely on it in case of emergency.

3.What to do to prevent infection                                               

    Get the vaccine shot before the flu epidemic!https://4.bp.blogspot.com/-Gob19MXY9gM/UQJe7kIOrcI/AAAAAAAALJU/SemkME2AjZ8/s1600/checkbox_checked.png

Influenza vaccines have the effect of reducing the flu development after infection. Even after the onset, it is said to be effective in preventing its aggravation.

It is desirable to take the vaccine shot by mid-December. In Japan, influenza is spread from December to April every year, and peaks from the end of January to the beginning of March. 

Insurance does not cover the vaccination cost. Therefore, you need to pay the full cost. The cost varies depending on the medical institutions.


    Wash your hands well when you come back from going out!https://4.bp.blogspot.com/-Gob19MXY9gM/UQJe7kIOrcI/AAAAAAAALJU/SemkME2AjZ8/s1600/checkbox_checked.png

Washing hands with running water and soap is effective to remove viruses on the fingers and body. Hand sanitizers with alcohol-based formulations are also effective.


    Keep a moderate humidity percentage!https://4.bp.blogspot.com/-Gob19MXY9gM/UQJe7kIOrcI/AAAAAAAALJU/SemkME2AjZ8/s1600/checkbox_checked.png

When the air is dry, defense function of airway mucosa is reduced. As a result, it’s easy to get the flu. Use a humidifier and try to keep a proper humidity percentage (50 to 60%).

    Take plenty of rest and eat balanced meals!https://4.bp.blogspot.com/-Gob19MXY9gM/UQJe7kIOrcI/AAAAAAAALJU/SemkME2AjZ8/s1600/checkbox_checked.png

Improving the body’s immunity is one way to fight the flu. Avoid getting too tired, and make sure to stay healthy.


    Avoid crowds and going out to busy areas!https://4.bp.blogspot.com/-Gob19MXY9gM/UQJe7kIOrcI/AAAAAAAALJU/SemkME2AjZ8/s1600/checkbox_checked.png

If you have to go out, wear a mask. 

<How to wash your hands>

Washing your hands is effective to wash off the virus.

When you come back from being out, or before you eat a meal, wash your hands well!


・The contents above are created with reference to the following information. Please note that if there is a change in the content of the reference source, it may take some time before it is reflected on this site.


・Ministry of Health, Labor and Welfare: “Influenza (general page)”


・Tokyo Metropolitan Government: “Tokyo Metropolitan Infectious Disease Surveillance Center”